Egg freshness test
Materials needed
*Raw eggs (a fresh one and two eggs, which are a week or two old)
*A bowl or glass of water
Method
1) Fill the bowl or glass with enough water to cover an egg.
2) Gently place one egg into the water.
3) Watch what happens: a fresh egg will sink and lie flat, an older egg will sink but stand upright, and a spoilt egg will float to the surface.
What happened?
As eggs age, air enters through their shells. More air makes them lighter, so the older eggs float.
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Floating and sinking egg
Materials needed
*Raw eggs: 2
*Tall clear glasses or clear jars: 2
*Water
*Tablespoons of salt per glass: 5-6
*Spoon
Method
1) Fill one glass with plain water and place an egg in it. It will sink.
2) Fill the second glass with water. Stir salt into it until it dissolves.
3) Place the second egg in the salty water. It will float!
What happened?
Salt water is denser than the egg, so the egg floats. In plain water, the egg is denser, which makes it sink.
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Bouncy egg
Materials needed
*Raw egg
*Clear glass or jar
*White vinegar
*Spoon
Methods
1) Place the raw egg gently in the glass or jar.
2) Pour vinegar into the glass or jar until the egg is fully covered. Bubbles will appear.
3) Leave it for 24 to 48 hours.
4) Carefully remove the egg and rinse it. The shell will have dissolved by now, leaving a soft, rubbery egg behind.
5) Try bouncing the rubbery egg gently from a small height.
What happened?
Vinegar (acetic acid) dissolves the eggshell (calcium carbonate). The thin membrane stays, making the egg soft and bouncy.